The present invention relates to a formulation and a method useful for increasing the essential oil content of aromatic crops. In particular, this invention relates to a formulation comprising an amino acid, such as an isomer of amino butyric acid, wherein the formulation is capable of increasing or enhancing the essential oil content in aromatic plants.
The concept of inducing resistance in plants in laboratories, glasshouse studies, and in the field has been demonstrated using abiotic and biotic elicitors, which may include complex carbohydrates, various amino and fatty acids, derivatives of salicylic, nicotinic and jasmonic acids, ethylene, glycoproteins, and the like. (Lyon et al., Plant Pathology, 44:407-27 (1995)).
Such elicitors have also been shown to induce other biochemical changes, which affect plants and plant cell systems, such as photosynthesis (Pancheva et al., Journal of Plant Physiology 149:57-63 (1996)), anthocyanin accumulation (Berglund et al., Journal of Plant Physiology, 141:596-600 (1993)) and flowering (Krajncic and Nemec, Journal of Plant Physiology, 146:754-756 (1995)). These findings indicate that elicitors act as signal molecules for gene expression in plants. However, compounds or chemicals (such as elicitors) capable of enhancing the yields of secondary metabolites (such as essential oil) in aromatic plants, in vivo, are not presently known in the art.
The essential oil of aromatic plants typically comprises a mixture of various terpenes, which are synthesized as a result of a large amount of enzyme activity in multibranched pathway(s). (Ram et al., Journal of Medicinal and Aromatic Plant Sciences, 19:24-27 (1997)). The present application examines how compounds such as the elicitors described above may affect the synthesis of essential oil while altering various biochemical pathways.
Amino butyric acid, a non-protein amino acid, has known biological effects in plants and animals. (Zimmerli et al., Proc. Nat""l Acad. Sci. USA 97:12920-12925 (2000)). Isomers of amino butyric acid have been identified as regulatory molecules in physiological processes of plants, for example in inducing resistance against phytopathogenic organisms. Examples of such activity include: inducing resistance against Peronospora parasitica in Arabidopsis (Zimmerli et al., Proc. Nat""l Acad. Sci. USA 97:12920-12925 (2000)); inducing resistance against Plasmopara viticola in grapes. (Cohen et al., Eur. J. Plant Pathol., 105:351-61 (1999)); and inducing resistance against Phytophthora infestans in tomatoes. (Cohen et al., Plant Physiology 104:59-66 (1994)).
However, the prior art has not examined the role that amino butyric acid may have in enhancing the synthesis and accumulation of essential oil in plants. Thus, the findings of the present invention may be useful in applications and industries such as plant-derived aromas and mediculture. In addition, increasing the essential oil content in aromatic crops may provide for minimizing the use of chemical fungicides.
Therefore, a need exists for a formulation and a method for enhancing or increasing the essential oil content or yields in aromatic crops. More particularly, a need exists to provide a formulation comprising, for example, a non-protein amino acid, such as DL-2 amino butyric acid to increase the synthesis and accumulation of the quantities of essential oil, in vivo, in aromatic plants.
The present invention relates to a formulation for and a method of enhancing or increasing the essential oil content in aromatic plants and other plants. It is an object to provide a chemical formulation and a method of applying the chemical formulation to aromatic plants in order to derive significant improvement in the content of essential oil in aromatic crops.
It is a further object of the present invention to provide a method of increasing the essential oil content in an aromatic plant wherein the growth of the plant is not negatively affected when the plant is sprayed or treated with the formulation at the onset of the plant""s maturity. Furthermore, the present invention seeks to provide a formulation and a method of treating aromatic plants with such a formulation in order to provide an environmentally safe method of increasing the essential oil content of aromatic plants or crops. The formulation described herein, as well as the method of treatment are environmentally safe in that the formulation comprises amino acids and are applied to the aromatic crops at low concentrations.
It is an object of the present invention to provide a chemical formulation, wherein the formulation comprises an amino acid (such as an isomer of amino butyric acid) and a carrier, and wherein the formulation may further comprise secondary metabolites. The formulation or the elicitor is capable of increasing the synthesis and accumulation of essential oil (which comprises a pool of secondary metabolites) in aromatic crops. Examples of aromatic crops to be used in the present invention include, but are not limited to, rose-scented geranium (Pelargonium graveolens) and menthol mint (Mentha arvensis). The present invention also provides for a method of increasing the synthesis and accumulation of essential oil in aromatic crops.
Accordingly, the present invention provides a formulation which is useful for increasing, in vivo, the synthesis and accumulation of essential oil in aromatic plants. The formulation used as an elicitor comprises an effective amount of a resistance inducer, such as an isomer of amino butyric acid or another amino acid. The formulation may further comprise secondary metabolites as well as a carrier.
In certain embodiments of the present invention, the resistance inducer used in the elicitor formulation may be one of the following: isonicotinamide; DL-2 amino butyric acid; 4-chloro salicylic acid; 2-amino isobutyric acid; o-acetyl salicylic acid; amino salicylic acid; salicylic acid; and 5-nitrosalicylic acid. In certain preferred embodiments of the present invention, the formulation comprises an effective amount of a non-protein DL-2 amino butyric acid. For example, in certain preferred embodiments, the formulation comprises DL-2 amino butyric acid at a concentration of from about 0.1 mM to about 4 mM in water.
The method of using the formulation of the present invention involves applying the formulation to an aromatic crop. For example, single or multiple doses of a solution of DL-2 amino butyric acid having a concentration of from about 0.1 mM to about 4 mM may be sprayed on aromatic crops such as menthol mint (Mentha arvensis) and rose-scented geranium (Pelargonium graveolens).
The application of the formulation to aromatic plants may occur at various stages within the growth or development of such aromatic plants. For example, in certain embodiments, a solution of DL-2 amino butyric acid may be applied 15 days prior to the harvesting of 100-day-old aromatic plants.
As stated earlier, the formulation comprising a solution of amino butyric acid or another amino acid may further comprise secondary metabolites. Such secondary metabolites may include alkaloids, fatty acids, proteins, and vitamins.
Many varieties of aromatic plants may be treated with the formulation disclosed in the present invention. Examples of aromatic plants which may be used include, but are not limited to, rose-scented geranium (Pelargonium graveolens); menthol mint (Mentha arvensis); Chamomilla recutita; Artemisia pallens; Cymbopogon winterianus; and the like. In certain preferred embodiments, the aromatic plants employed are Mentha arvensis and Pelargonium graveolens because of their oil-yielding capacity. Furthermore, the process of applying the formulation to a plant in order to enhance the plant""s essential oil content may employ medicinal plants, oilseed crops, pulses, and food crops.
In certain embodiments of the present invention, the essential oil content of the aromatic plants treated by the formulation of the present invention is increased by about 20% to about 46%. For example, when Pelargonium graveolens is sprayed with a solution of DL-2 amino butyric acid, its essential oil content is increased by about 46%. Similarly, when Mentha arvensis is sprayed with a solution of DL-2 amino butyric acid, its essential oil content is increased by about 27%. The working examples described later in the application illustrate these and other findings.
The present invention also provides for a method of increasing the essential oil content in aromatic plants and other plants. In the present method, certain resistance inducers are first tested to determine whether or not they improve growth in the selected aromatic plants. A resistance inducer, such as an isomer of amino butyric acid or another amino acid, is then selected and included in a formulation. The formulation comprises a solution of the resistance inducer as well as a carrier and/or secondary metabolites.
Subsequently, an aromatic plant is selected, possibly based on its overall growth and yield of essential oil. The selected aromatic plant is then treated with secondary metabolites. The optimal concentration of the resistance inducer in the formulation is then determined, and the formulation (for example, a solution of DL-2 amino butyric acid) is applied to the aromatic plants. In certain embodiments of the present method, the resistance inducer used is an amino butyric acid or another amino acid, for example, isonicotinamide, DL-2 amino butyric acid, 4-chloro salicylic acid, 2-amino isobutyric acid, o-acetyl salicylic acid, amino salicylic acid, salicylic acid, or 5-nitrosalicylic acid.
In the present method, the aromatic plants may be treated with secondary metabolites, such as alkaloids, fatty acids, proteins, and vitamins. Aromatic plants whose essential oil content may be increased by the present method include, but are not limited to, rose-scented geranium (Pelargonium graveolens), menthol mint (Mentha arvensis), Chamomilla recutita, Artemisia pallens, and Cymbopogon winterianus. Aromatic plants such as Mentha arvensis and Pelargonium graveolens are used in certain preferred embodiments of the present invention because of their high capacity for yielding essential oil. Furthermore, in other embodiments of the present method, medicinal plants, oilseed crops, pulses, and food crops are treated the formulation according to the present invention.
The following examples are intended to illustrate the invention and should not be construed as limiting the invention in any way.